The central nucleus of the amygdala (CNA) and the bed of nucleus of the stria terminalis (BNST) have been implicated in gastric secretory functions and in the etiology of stress-induced gastric ulcers and hemorrhages. The studies of this proposal are intended to provide data clarifying the role of the CNA and BNST in gastric functions by using anatomical, histochemical and immunocytochemical techniques. These methods will be applied in studying the organization and the possible neurotransmitters used by CNA and/or BNST pathways to vagal gastric regions in the medulla of the rat. Information provided by the study of the biochemical and anatomical substrates mediating the development of stress-induced ulcers may aid in the clinical treatment of such problems. The topography of the CNA and BNST axonal projections to the vagal autonomic nuclei (dorsal motor nucleus of the vagus nerve, nucleus ambiguus and nucleus tractus solitarius) will be analyzed using anterograde and retrograde tracing techniques. The hypothesis that certain neuropeptides are contained within these efferent pathways will be tested using various combinations of intracranial lesions, retrograde tracers and immunocytochemistry. The hypothesis that the CNA and/or BNST are connected monosynaptically with vagal motor neurons innervating the stomach will be tested using electron microscopic and anterograde and retrograde pathway tracing techniques.